Proximity fuzes

ABSTRACT

1. In an ordnance missile, a proximity-type ordnance fuze adapted to detonate said missile when said missile passes through the shock-wave front produced by a high velocity target, said fuze comprising in combination: a pressure-sensitive switch; said switch comprising a cylindrical housing, a perforated electrically conductive diaphragm mounted in said housing, the diameter of said diaphragm being substantially normal to the axis of said missile and the longitudinal axis of said cylindrical housing, one end of said housing being internally threaded an externally threaded ring adapted to mate with the threaded end of said housing and movable therein in a direction parallel to said axis of said missile, said ring and diaphragm being positioned such that movement of said ring in said direction causes said ring to press against said diaphragm thereby increasing the tension of said diaphragm, an electrical contact fixed in said housing substantially perpendicular to the diameter of said diaphragm, said contact extending adjacent to and spaced from said diaphragm, said contact being insulated from said housing, said diaphragm being sufficiently flexible so that said diaphragm can contact said contact as a result of abrupt changes in pressure encountered when said missile passes through said shockwave front; detonation means adapted to detonate said missile in response to the application of a firing signal thereto; and an energy source connected in series with said detonation means and said switch, the contacting of said diaphragm and contact causing a firing signal to be applied by said energy source to said detonation means thereby causing detonation of said missile.

United tates iet [151 3,677,184 Rabinow et ai. [45] Judy 18, 1972 s41 PROTY FUZES EXEMPLARY CLAIM [72] Inventors: Jacob Rabinow, Takoma Park; Israel Rotl. in an ordnance missile, a proximity-type ordnance fuze kin, Silver Spring; Bethesda, all of Md.

Alien V. Astin,

adapted to detonate said missile when said missile passes through the shock-wave front produced by a high velocity tar- [73] Assignee: The United Stem oi America as S i, d fuze comprising in eombinatioma pressure-sensitive represented by the secretary of the Army switch; said switch comprising a cylindrical hous|ng, a perforated electrically conductive diaphragm mounted In said [22] Filed: 1955 housing, the diameter of said diaphragm being substantially [21] A l. No.: 528,856 normal to the axis of said missile and the longitudinal axis of said cylindrical housing, one end of said housing being internally threaded an externally threaded ring adapted to mate with the threaded end of said housing and movable therein in a [52] US. Cl ..l02/70.2P direction parallel to said axis of said missile, said ring and [5 i] In. F426 F426 F426 dia hragm being positioned uch that movement of [58] Field of Search ..l02/70.2, 70.2 P, 68, 18; in said direction causes i i to press against said 310/87 8 diaphragm thereby increasing the tension of said diaphragm,

an electrical contact fixed in said housing substantially perpendicular to the diameter of said diaphragm, said contact ex- 56] References cued tending adjacent to and spaced from said diaphragm, said contact being insulated from said housing, said diaphragm being UNITED STATES PATENTS sufficiently flexible so that said diaphragm can contact said 2,536,327 1/1951 Tolson ....l02/70.2 P contact as a result of abrupt changes in pressure encountered 2,587,308 2/1952 Fishe ..310/8.7 when said missile passes through said shock-wave front; 2,633,543 3/1953 H uatt detonation means adapted to detonate said missile in response 913,524 2/1909 Leon u to the application of a firing signal thereto; and an energy ource connected in eries detonation means and Primary Examiner-Benjamin A. Borchelt Assistant Examiner-Thomas H. Webb Attorney-Harry M. Sarogowitz, Edward J. Kelly and Herbert Berl said switch, the contacting of said diaphragm and contact causing a firing signal to be applied by said energy source to said detonation means thereby causing detonation of said missile.

1 Claim, 4 Drawing Figures SUPERSONIC Patented July 18, 1972 2 Sheets-Sheet l SUPERSONIC TARGET PROJECTILE DETONATOR SHOCK-WAVE WARHEAD ggi'g SHOCK- WAVE SAFETY a ARMING FRONT DEVICE \33 2|d 3| FBARIUM 3 36 HIGH PASS 37 I I TITANATE I Q2? FILTER THYRATRON F nETONATOR I TRANSDUCER 38/ L J I i I: E,

DETONATOR DIRECTION OF MISSILE E1g E- T RAJECTORY I I I I I I I I l I I I I INVENTORS Jacob Rab/now lsrae/ Raf/rm A/len V Asf/n ATTORNEYS Patented July 18, 1972 2 Sheets-Sheet 2.

INVESTORS Jacob Rab/now /srae/ Raf/rm A/len M A5170 .5, mmQw 0Q ATTORNEYS 1 ll III .I. I u E .51 M32 wa on zomEEE A E 520 wwE IQI wzwzommwm 5:513 r m wwii M2282 ESE oh 520 20E Sci A wmfi zoi wzwzoawwm EEIQSE PROXIMI'I'Y FUZES The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to us of any royalty thereon.

This invention relates to ordnance fuzes and particularly to ordnance fuzes for use against targets having supersonic or high subsonic velocities. Principally, the invention provides proximity-types fuzes that are sensitive to encounter with the shock wave associated with such targets. The invention also provides proximity fuzes adapted to produce a first pattern of warhead fragmentation upon approach to a target from a generally forward direction with respect to the target trajectory but to produce a second pattern of warhead fragmentation upon approach to a target from a generally rearward direction with respect to the target trajectory.

It is well known that an object traveling through the atmosphere at supersonic speed gives rise to a shock wave having a front that advances with the speed of the object but that extends beyond the periphery of the object. It is known also that certain portions of objects traveling at high subsonic speeds may give rise to similar shock waves having fronts extending beyond the periphery of the object. It is known furthermore that the shock-wave front associated with an object generally constitutes a very sharply defined boundary between two regions a first region extending between the boundary and the object and a second region extending outward from the boundary away from the object that differ substantially from each other in pressure and in temperature. In typical embodiments, our invention provides proximity fuzes responsive to one or more of the changed ambient conditions encountered by a projectile as it passes through a shock-wave front associated with a target. Our invention also provides proximity fuzes that sense whether they are approaching a target from a generally forward or a generally rearward direction, and that cause firing of a first-positioned detonator in the forward-approach case but of a second-positioned detonator in the rearward-approach case, the pattern of war head fragmentation being dependent on which detonator is fired.

The advantages of proximity-type ordnance fuzes are well known. The effectiveness of proximity-fuzed missiles may be many times greater than that of contact-fuzed missiles that explode only in response to direct contact with the target. Known proximity fuzes have been principally of the radio type.

An object of the present invention is to provide a reliable, economical proximity-type ordnance fuze for use against supersonic or near-supersonic targets.

Another object is to provide a passive-type proximity fuze i.e., a fuze that does not have to radiate energy in order to sense a target for use against supersonic or near-supersonic targets.

Still another object is to provide a proximity fuze having high immunity to countermeasures.

Yet another object is to provide a proximity fuze adapted to produce a first pattern of warhead fragmentation upon approach to a target from a generally forward direction with respect to the target trajectory but to produce a second pattern of warhead fragmentation upon approach to a target from a generally rearward direction with respect to the target trajectory.

Other objects, aspects, uses, and advantages of the invention will become apparent from the following description and from the accompanying drawings, in which FIG. 1 is a block diagram representing an encounter between a supersonic target and an ordnance projectile fuzed in accordance with our invention.

FIG. 2 is a block diagram of a form of our invention using a barium titanate transducer and a high-pass filter.

FIG. 3 is a longitudinal section of a pressure-responsive switch adapted to use in our invention.

FIG. 4 is a block diagram of another proximity fuze in accordance with our invention.

In FIG. 1 an ordnance projectile 12 approaches a target 13. Target 13 is traveling at supersonic speed and gives rise to an associated shock wave having a front 14 that travels at the speed of target 13. Projectile 12 is provided with a shockwave-sensitive device 21. When projectile 12 crosses shockwave front [4, device 21 is subjected to, and actuated by, an abrupt change in one or more ambient conditions. Device 21, thus actuated, fires a detonator 31 that in turn fires a warhead 32. A safety-and-anning device 33, which may be of a wellknown design, is associated with detonator 31 and prevents the functioning of warhead 32 until projectile 12 is in flight and is a safe distance from using personnel.

Device 21 is preferably a pressure-sensitive device actuated by the abrupt change of pressure encountered in passing through shock-wave front 14 and preferably gives an electrical output signal in response to such actuation, such electrical signal being applied to detonator 31. However, a suitable temperature-sensitive device is also among the alternative forms that shock-wave-sensitive device 21 may take.

FIG. 2 shows a preferred pressure-actuated form of the invention in which a pressure-sensitive device 21d fires a detonator 31 in response to a shock wave. Device 21d comprises a barium-titanate transducer 35 adapted to generate a steep electrical pulse in response to the abrupt change of pressure encountered in passing through shock-wave front 14 (FIG. 1). It will be understood that such a steep electrical pulse contains energy broadly distributed over a wide frequency spectrum. This pulse is amplified by an amplifier 36, filtered by high-pass filter 37, and applied as a firing signal to a thyratron 38. When thyratron 38 fires it in turn fires detonator 31.

High-pass filter 37 in FIG. 2 is preferably provided in order to discriminate against noise and microphonics that may be generated by transducer 35 or amplifier 36 before shock-wave front 14 is encountered. In the absence of filter 37, such noise and rnicrophonics might cause premature firing of thyratron 38 and detonator 31. It will be understood that transducer 35 must therefore have adequate response at the high frequencies passed by filter 37. Barium titanate is well adapted to provide transducers having a good high-frequency response. In general the change in pressure encountered in passing through a shock-wave front is very great; there is no practical difficulty about providing a transducer 35 that will, upon passing through a shock-wave front, generate high-frequency energy many times greater in amplitude than that due to noise and microphonics before the front is encountered.

In FIG. 3 is shown another form of pressure-sensitive device 2le adapted to cause firing of detonator 31 upon passing through a shock-wave front. Device 2le is a form of switch sensitive to a pressure impulse. The most important features of device 2le include a metallic diaphragm 51 supported, preferably under tension, between two electrical contacts 52 and S3. The orientation of device 2le within projectile 12 is preferably such that diaphragm 51 is normal to the axis of projectile 12. When device 21e encounters a shock-wave front, the shock wave applies a large force to diaphragm 51, causing the central region of diaphragm 51 to become displaced and to make electrical contact with one or successively with one and then the other of contacts 52 and 53. When diaphragm 51 makes such electrical contact it closes an electrical circuit comprising detonator 31 and a power source 54, thereby applying electric power to, and causing detonation of, detonator 31.

Diaphragm 51 may conveniently be supported in a cylindrical metallic housing 61. Forward contact 52 may be insulatedly supported on an end plate or bridge 62. Bridge 62 is preferably provided with large ports 65 to minimize the impedance offered by bridge 62 to the transient flow of air into or out of the forward end of housing 61. lmperforate plate 63 provides a substantially hermetic closure at the rearward end of housing 61. Rearward contact 53 may be insulatedly supported on end plate 63. Suitable tension may conveniently be applied to diaphragm 51 by means of a threaded tension ring 67 mounted inside housing 61. After diaphragm 51 has been placed under suitable tension, the spacing of contacts 52 and 53 from diaphragm 51 may be adjusted. This spacing should be great enough to obviate the possibility of premature accidental contact of diaphragm 51 with contacts 52 or 53 as a result of vibration or shock during projectile launching and flight before a shock wave is encountered. Because of the relatively large force applied to diaphragm 51 upon encounter with a shock-wave front, this requirement is not difficult to satisfy.

Diaphragm 51 is preferably provided with a large number of small perforations 71. These perforations 71 permit air to flow through diaphragm 51 during flight prior to shock-wave encounter, thus minimizing the displacement of diaphragm 51 due to the impingement of air prior to shock-wave encounter. If these perforations 71 are small they present a high impedance to the abrupt pressure change produced by encounter with a shock-wave front, so that upon such encounter diaphragm 51 may become displaced almost as forcibly as if diaphragm 51 were imperforate. Fine wire mesh is a suitable material for diaphragm 51.

Upon encounter with a shock-wave front, diaphragm 51 normally moves first rearward and then forward with respect to its static position. Present knowledge indicates that the amplitude of the forward motion may in some cases exceed the amplitude of the initial rearward motion. Principally for this reason, to insure maximum reliability, we prefer to provide both forward and rearward contacts 52 and 53, connected in parallel, as shown. However, it will be understood that provision of only a single contact 52 or 53 may be sufficient.

It will be understood that the amount of electrical energy supplied by device 2le to detonator 31 upon shock-wave encounter will depend in part upon the time duration of the contact between diaphragm 51 and electrical contacts 52 and/or 53. It will be understood that a thyratron or other triggering or relay device may be interposed between device Zle and detonator 31.

In FIG. 4 we show how to provide a proximity fuze adapted to produce a first pattern of warhead fragmentation upon approach to a target from a generally forward direction with respect to the target trajectory but to produce a second pattern of warhead fragmentation upon approach to a target from a generally rearward direction with respect to the target trajectory.

It will be appreciated that the optimum burst pattern for a projectile passing through a particular detonation position (with respect to a target) from a forward direction will not necessarily be the same as for a projectile passing through the same detonation point from the rearward direction. It is known that detonation of a warhead by means of a detonator at one end of the warhead generally adds to the warhead fragmentation pattern a component of motion in the direction of the other end of the warhead.

In FIG. 4 a shock-wave-sensitive device 21f is adapted to fire a forward-positioned detonator 31a upon passing through a shock-wave front from the side away from the target, but to fire a rear-positioned detonator 31b upon passing through a shock-wave front from the side towards the target. Device 21f comprises a piezoelectric transducer 76 connected to give a positive electrical output signal in response to an increase in pressure and to give a negative electrical output signal in response to a decrease in pressure. The output of transducer 76 is connected to an amplifier 78 adapted to respond only to positive pulses and to another amplifier 79 adapted to respond only to negative pulses. A positive pulse produced by transducer 76 is amplified by amplifier 78 and is utilized to fire rear-positioned detonator 31a; a negative pulse produced by transducer 76 is amplified by amplifier 79 and is utilized to tire forward-positioned detonator 31b.

It will be understood that shock-wave-responsive fuzes in accordance with our invention are adapted to respond to encounter with a shock-wave front regardless of whether the projectile carrying the fuze is traveling at subsonic or supersonic speed.

We prefer to provide auxiliary contact-detonatrng means for projectiles fuzed in accordance with our invention, so that if a projectile should not be detonated by encounter with a shock-wave front it will nevertheless be detonated if it makes a direct hit on a target.

It will be apparent that the embodiments shown are only exemplary and that various modifications can be made in construction and arrangement within the scope of the invention as defined in the appended claims.

We claim:

1. In an ordnance missile, a proximity-type ordnance fuze adapted to detonate said missile when said missile passes through the shock-wave front produced by a high velocity target, said fuze comprising in combination: a pressure-sensitive switch; said switch comprising a cylindrical housing, a perforated electrically conductive diaphragm mounted in said housing, the diameter of said diaphragm being substantially normal to the axis of said missile and the longitudinal axis of said cylindrical housing, one end of said housing being internally threaded, an externally threaded ring adapted to mate with the threaded end of said housing and movable therein in a direction parallel to said axis of said missile, said ring and diaphragm being positioned such that movement of said ring in said direction causes said ring to press against said diaphragm thereby increasing the tension of said diaphragm, an electrical contact fixed in said housing substantially perpendicular to the diameter of said diaphragm, said contact extending adjacent to and spaced from said diaphragm, said contact being insulated from said housing, said diaphragm being sufficiently flexible so that said diaphragm can contact said contact as a result of abrupt changes in pressure encountered when said missile passes through said shock-wave front; detonation means adapted to detonate said missile in response to the application of a firing signal thereto; and an energy source connected in series with said detonation means and said switch, the contacting of said diaphragm and contact causing a firing signal to be applied by said energy source to said detonation means thereby causing detonation of said missile. 

1. In an ordnance missile, a proximity-type ordnance fuze adapted to detonate said missile when said missile passes through the shock-wave front produced by a high velocity target, said fuze comprising in combination: a pressure-sensitive switch; said switch comprising a cylindrical housing, a perforated electrically conductive diaphragm mounted in said housing, the diameter of said diaphragm being substantially normal to the axis of said missile and the longitudinal axis of said cylindrical housing, one end of said housing being internally threaded, an externally threaded ring adapted to mate wiTh the threaded end of said housing and movable therein in a direction parallel to said axis of said missile, said ring and diaphragm being positioned such that movement of said ring in said direction causes said ring to press against said diaphragm thereby increasing the tension of said diaphragm, an electrical contact fixed in said housing substantially perpendicular to the diameter of said diaphragm, said contact extending adjacent to and spaced from said diaphragm, said contact being insulated from said housing, said diaphragm being sufficiently flexible so that said diaphragm can contact said contact as a result of abrupt changes in pressure encountered when said missile passes through said shockwave front; detonation means adapted to detonate said missile in response to the application of a firing signal thereto; and an energy source connected in series with said detonation means and said switch, the contacting of said diaphragm and contact causing a firing signal to be applied by said energy source to said detonation means thereby causing detonation of said missile. 